Construction of a standard velocity structural madel and a standard wave propagation madel in Japan

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We compiled and developed a standard 3-D velocity structure model (velocity, density and Q ) in Japanese Islands to understand long-period ground motions. Then we calculate ground motions (or waveforms) by mean of FDM and three-dimensional Born kernels using this velocity structure model. Also, we operate PC-based analysis system to continuously monitor long-period (20-50 sec) seismic wavefield to simultaneously determine origin time, location and seismic moment tensor of seismic in realtime(GRiD MT : Grid-based RealtIme Determination of Moment Tensors URL : http : //wwweic.eri.u-tokyo.ac.jp/GRiD MT/).Summary is as follows :(1) We analyzed waveform data from a dense nation-wide strong-motion network (K-NET and KiK-net) for SE Off-Kii Peninsula (Mw7.4) earthquake of 5 September 2004 that occurred within then Nankai Trough. The observational data and a corresponding computer simulation using this velocity structure model clearly demonstrate that long-period ground motion.(2) A whole mantle SH velocity model is obtained by using a unique data set and technieues of 3-D Born kernels.(3) GRiD MT detects earthquakes and determines the source parameters with a high level of precision and complete automation within three minutes of the earthquake occurrence.